The invention disclosed herein pertains generally to gas insulated, high-voltage electric lines and more particularly to arrangements for insulating high-voltage conductors within a gas-filled pipe jacket.
U.S. Pat. No. 2,428,051 discloses a high-voltage line wherein a conductor is arranged within a pipe jacket and is centrally supported within the pipe jacket by three radially directed insulators, all of which insulators lie in the same plane. The insulators are bolted to the conductor. The end of each insulator facing an inner wall of the pipe jacket carries a spring-like element for holding the insulators at their positions within the pipe jacket. When the insulators, together with the conductor, are inserted into the pipe jacket, friction between the ends of the insulators and the pipe jacket results in metal particles or chips being rubbed off the pipe jacket. These undesirable chips remain inside the pipe jacket and are almost impossible to remove.
The published German patent application No. 21 47 787 (corresponding to U.S. Pat. No. 3,786,174) discloses a high-voltage line wherein a conductor is arranged within a pipe jacket and held in place by three radially directed insulators. Two of the insulators are rigidly connected to an insulating sleeve which encircles the conductor, while the third insulator is in the form of an insulating leg whose radial extent can be shortened by pressing against a spring. The conductor together with the insulators is inserted into the pipe jacket by means of a carriage assembly. The carriage assembly holds the insulating leg at a shortened radial position so that there is no contact between the insulators and the pipe jacket during the insertion of the conductor and the insulators into the interior of the pipe jacket. When the proper axial position is reached within the pipe jacket, the carriage assembly is pulled out, the spring of the shortened insulator leg presses the leg against the inner surface of the pipe jacket, thereby fixing the position of the conductor and the insulators within the pipe jacket. However, this arrangement is relatively complicated and requires the repeated use of the carriage assembly for positioning each set of insulators.
Accordingly, a primary object of the present invention is to provide an improved, gas insulated, high-voltage line which includes a conductor, encircled by one or more sets of radially directed insulators, which conductor is centrally arranged within a pipe jacket, and which conductor and insulators may be relatively easily inserted into the pipe jacket without friction between the insulators and the pipe jacket and without abrading metal chips from an inner wall of the pipe jacket.
A further object of the present invention is to provide an improved, gas insulated, high-voltage line which makes allowance for a radial, thermal expansion of the centrally arranged conductor.
Yet another object of the present invention is to provide a method and a tool for readily inserting the conductor and one or more sets of radially directed insulators into the interior of the pipe jacket.
Yet a further object of the present invention is to provide an improved, gas insulated, high-voltage line which includes a conductor, encircled by one or more sets of radially directed insulators, which conductor is centrally arranged within a pipe jacket, as well as a tool for easily inserting the conductor and insulators into the interior of the pipe jacket, which high-voltage line and tool are relatively simple.
A gas insulated, high-voltage electric line, according to the present invention, includes a cylindrical conductor which is centrally arranged within a pipe jacket. A plurality of insulators is arranged about the periphery of the conductor, and a spring-like element is arranged between each insulator and the conductor. The spring-like elements urge the insulators radially outwardly toward, and into contact with, an inner surface of the pipe jacket. The insulators are movable, relative to the pipe jacket, along a longitudinal axis of the pipe jacket.
A method for assembling the high-voltage electric line, according to the present invention, includes the step of mounting at least two sets of radially directed insulators onto the conductor of the high-voltage line. Each of the insulators includes a resilient member interposed between the conductor and the insulator. All of the insulators are simultaneously urged radially downwardly toward the conductor to produce a clearance between an outer end of each of the insulators and an inner surface of the pipe jacket of the high-voltage line. The conductor and the insulators are then moved into an interior of the pipe jacket until the first set of insulators has been moved to a desired axial location. All of the insulators are released to permit the resilient members interposed between the conductor and the first set of insulators to urge the first set of insulators radially outwardly into engagement with the inner surface of the pipe jacket. The second set of insulators is then engaged and urged radially downwardly toward the conductor. Then the conductor and the second set of insulators are moved further into the interior of the pipe jacket until the second set of insulators has been moved to a desired axial location. The second set of insulators is then released to permit the resilient members interposed between the conductor and the second set of insulators to urge the second set of insulators radially outwardly into engagement with the inner surface of the pipe jacket.
An apparatus, referred to herein as a clamping chuck, for inserting a conductor having at least one row of insulators mounted on the conductor into an interior of a pipe jacket, according to the present invention, includes at least one longitudinal member having jaws which may engage and urge the at least one row of insulators radially inwardly toward the conductor.